Biomedical subjects
Publications and source records attributed to M Coulomb.
Five percent of pleural tumors are benign. Solitary fibrous tumors are the most frequent. We recall the clinical and pathological features and present the radiographic, computed tomographic and magenetic resonance imaging results obtained for the main types of benign tumors of the pleura.
The purpose of this study was to prove the feasibility of 3D reconstructions of the diaphragm during the respiratory cycle using EPI sequences (EPI acquisition, 270 ms/image, on a healthy subject breathing spontaneously and at 0.1 Hz). Continuously recorded respiratory signal allowed for retrospective synchronization with respiratory phases for reconstruction of successive diaphragm surfaces using a specifically designed software. Displacements, area and volume changes of the diaphragm were quantified. Our measurements were comparable with the data in the literature. Reconstructed surfaces allowed in vivo diaphragm dynamic evaluation in terms of displacements, area and volume variations. EPI has adequate spatial and temporal resolution for studying diaphragm dynamics during natural breathing.
PURPOSE: To describe the imaging features of bronchial carcinoids and to define the role of CT as a diagnostic and pretherapeutic tool. MATERIALS AND METHODS: We performed a retrospective study including 54 carcinoids. We evaluated and compared the clinical, radiographic, CT, fiberoptic, and pathologic data. RESULTS: At presentation, the mean age was 48.5 years (14-81) and patients mainly complained of signs related to bronchial obstruction (55.7%). 72% of bronchial carcinoids were located in the proximal airway. CT showed calcifications in 26% of 54 cases and contrast enhancement in 60%. Typical carcinoids differed from atypical carcinoids in their size and lymph node extension. As compared to fiberoptic bronchoscopy, CT identified proximal carcinoids with exo-bronchial extension (7.4%), peripheral tumors (20.4%), and parenchymal complications. The sensitivity and predictive positive-value of CT for lymph node extension was 28% and 20%, respectively. CONCLUSION: CT is a useful technique for diagnosing and localizing bronchial carcinoids. The results of CT in determining lymph node extension is disappointing, and should raise caution in case of localized treatment using fiberoptic bronchoscopy.
The objective was to evaluate the helical CT (HCT) criteria that could indicate severe pulmonary embolism (PE). In a retrospective study, 81 patients (mean age 62 years) with clinical suspicion of PE explored by HCT were studied. The patients were separated into three different groups according to clinical severity and treatment decisions: group SPE included patients with severe PE based on clinical data who were treated by fibrinolysis or embolectomy ( n=20); group NSPE included patients with non-severe PE who received heparin ( n=30); and group WPE included patients without PE ( n=31). For each patient we calculated a vascular obstruction index based on the site of obstruction and the degree of occlusion in the pulmonary artery. We noted the HCT signs, i.e., cardiac and pulmonary artery dimensions, that could indicate acute cor pulmonale. According to multivariate analysis, factors significantly correlated with the severity of PE were: the vascular obstruction index (group SPE: 54%; group NSPE: 24%; p<0.001); the maximum minor axis of the left ventricle (group SPE: 30.2 mm; group NSPE: 40.4 mm; p<0.001); the diameter of the central pulmonary artery (group SPE: 32.4 mm; group NSPE: 28.3 mm; p<0.001); the maximum minor axis of the right ventricle (group SPE: 47.5 mm; group NSPE: 42.7 mm; p=0.029); the right ventricle/left ventricle minor axis ratio (group SPE: 1.63; group NSPE: 1.09; p<0.0001). Our data suggest that hemodynamic severity of PE can be assessed on HCT scans by measuring four main criteria: the vascular obstruction index; the minimum diameter of the left ventricle; the RV:LV ratio; and the diameter of the central pulmonary artery.
The aim of this study was to compare helical CT with fiberoptic bronchoscopy findings to appraise the medium-term results of proximal-airways stenting. Twenty-five patients with 28 endobronchial metallic stents inserted for local advanced malignancy ( n=13) or benign diseases ( n=12) underwent follow-up CT from 3 days to 50 months (mean 8 months). All studies were obtained using helical CT with subsequent multiplanar reformation and three-dimensional reconstruction including virtual bronchoscopy. The location, shape, and patency of stents and adjacent airway were assessed. The results of CT were compared with the results of fiberoptic bronchoscopy obtained with a mean delay of 2.5 days (SD 9 days) after CT scan. Twelve stents (43%) remained in their original position, patent and without deformity. Sixteen stents were associated with local complications: migration ( n=6); external compression with persistent stenosis ( n=4); local recurrence of malignancy ( n=4); fracture ( n=1); and non-congruence between the airway and the stent ( n=1). The CT demonstrated all the significant abnormalities demonstrated at fiberoptic bronchoscopy except two moderate stenoses (20%) related to granulomata at the origin of the stent. Ten of 14 stents inserted for benign conditions were without complications as compared with 2 of 14 in malignant conditions ( p=0.008). Computed tomography is an accurate noninvasive method for evaluating endobronchial stents. The CT is a useful technique for follow-up of patients who have undergone endobronchial stenting.
A 70-year-old man with recurrent undiagnosed episodes of bronchial cast expectoration and pulmonary infiltrates on chest radiography for 15 years is described. The diagnosis of chyloptysis was established by chemical analysis of the bronchial aspiration. We emphasize the radiological findings of this rare observation. The CT-associated lymphangiography showed mediastinal lymphangiectasis with retrograde opacification of mediastinal and hilar lymph nodes as well as submucosal lymphatic vessels protruding into the lumen of the tracheo-bronchial tree without evidence of thoracic duct obstruction as well as a "crazy-paving appearance." Congenital incompetence of the valves of the lymphatic vessels originating from the thoracic duct is held to be the cause. Chyloptysis and pulmonary lymphatic disorder should be sought in cases of bronchial cast expectoration.
Traumatic ruptures of the pericardium with cardiac herniation are infrequent, and their radiological pattern little familiar, so that they are often missed preoperatively. Few reports have emphasised the use of a CT scan as a tool for diagnosis and CT scan signs have not been well documented. We report on two cases of traumatic herniation of the heart for which a CT scan brought a major contribution for diagnosis. We describe the presence of an empty pericardial sac on CT slices which allowed us to diagnose the cardiac herniation. These observations demonstrate that CT scans can contribute to the diagnosis of pericardial rupture with cardiac herniation.
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Helical computed tomography (HCT) allows for volume acquisition of the entire thorax during a single apnoea. Combination of HCT acquisition with synchronous vascular enhancement gives rise to HCT angiography (HCTA). In the last decade, HCT and HCTA have revolutionized the diagnosis of thoracic diseases, modifying many diagnostic algorithms. Because HCT provides for a true volume acquisition free of respiratory misregistration, three-dimensional (3D) rendering techniques can be applied to HCT acquisitions. As these 3D rendering techniques present the HCT information in a different format to the conventional transaxial CT slices, they can be summarized as virtual tools. The purpose of this review is to give the readers the most important technical aspects of virtual tools, to report their application to the thorax, to answer clinical and scientific questions, and to stress their importance for patient management, clinical decision making, and research.
PURPOSE: European directive 97/43 specifies that the dose delivered to the patient during a radiological procedure should be estimated. In order to prepare for implementation of this new regulation, we have studied the dose delivered during spiral CT acquisition. MATERIALS AND METHODS: We have studied the influence of slice thickness, pitch, tube voltage and intensity, and acquisition volume length. We present measurements for single and dual detector CT scanners. We used a pencil ionization chamber to measure air kerma. We measured absorbed dose in water with a waterproof ionization chamber set in a semi-customized phantom filled with water. Chambers were set on the rotation axis of the CT scanners. We studied the dose outside the acquisition volume. RESULTS: We quantified the influence of each parameter on the absorbed dose. We used our measurements to calculate the dose for different acquisition protocols. Also we evaluated the dose to organs distant from the acquisition area. CONCLUSION: This study is one step toward a systematic estimation of the dose delivered to patient during helical CT exams. To use these results in daily practice, we have to develop software using our measurements.
UNLABELLED: To make the surgical procedure safer and more precise in FESS, a non-invasive markerless computer-assisted system (CAS) is described for intra-operative navigation whenever the critical regions may be affected by surgical manipulation. PATIENTS AND METHODS: Twenty patients with benign diseases of the paranasal sinuses were treated by Computer Assisted Video-endoscopic surgery, between December 1997 and March 1998. For the determination of accuracy and reproducibility of the system, ten anatomical landmarks on each side of the paranasal sinuses were chosen and measured. All of these points were identified on the direct live video-endoscopy image and compared to those obtained with the Optical Digitizing System (Flashpoint 5000(R)), on axial, coronal and sagittal view. The Optical Localizer we used detects the position of the relative coordinates of two rigid bodies made of IR-LED's each, one rigid body is secured to the head' of the patient with a headset, so that patient motion can be tracked, and the second rigid body attached to the operating instrument, leading to direct localization of the tip of the instrument. We use a markerless, skin surface-based registration method, which has the advantage to avoid doing a second CT scan examination usually performed to process the position of the fiducial markers. We register the data from the patient's usual paranasal CT scan. RESULTS: Computer-assisted surgery does not increase significantly the duration of the operation. Our markerless skin surface points registration method is reliable enabling of the movements patient's head during the procedure. Computer assistance can be used in almost any type of endoscopic sinonasal procedure. We obtained a registration and calibration accuracy of less than 1.5 mm in 89.2% of cases. CONCLUSION: CAS enables the surgeon to have a more thorough understanding of the complicated anatomy of paranasal sinuses, and may be especially helpful in revision surgery when normal anatomic landmarks are lacking. Due to the passive optical technology (Passive Polaris(R)), we are continuing clinical studies in ENT surgery in order do improve the system and to simplify its current management.
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Interpretation of chest X-ray relies not only on morphological criterion but also on physiological bases. Vascular opacities represent 80% of visible structures in the lung area; the contour of the heart and large vessels are well recognized. In the first part we review the current knowledge about the physiology of the pulmonary circulation and its factors of regulation. In the second part we present the reading principals of a chest X-ray obtained in an erect patient at the end of inspiration. A check list should be verify in every patient: pulmonary flow distribution (ratio apex/basis); size of small vessels in the periphery of both lungs; Simon's line; shape of vessels; ratio of the artery/bronchus diameter; size and shape of the heart; diameters of aorta, right pulmonary artery, and azygos vein. In the last part, we present the main pathological patterns: diffuse increase of pulmonary flow; pulmonary venous hypertension; pulmonary arterial hypertension; localized changes of the pulmonary blood flow in which the role of expiratory X-ray is emphasized. Many pitfalls are identified: egalisation of the ratio apex/basis; enlargement of the vascular pedicle; enlargement of the azygos vein.
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We report the case of a 60-year-old woman with a recent history of a cerebrovascular accident. Because of clinical suspicion of pulmonary embolism and negative Doppler ultrasound findings of the lower limbs, spiral computed tomography of the pulmonary artery was performed and demonstrated pulmonary emboli. We emphasize the role of computed tomography of the abdomen, performed 3 min after the thoracic acquisition, which showed an unsuspected thrombus within the abdominal aorta and the left renal artery with infarction of the left kidney. Paradoxical embolism was highly suspected on computed tomography data and confirmed by echocardiography which demonstrated a patent foramen ovale.
OBJECTIVE: The purpose of this retrospective study was to determine the added diagnostic value, if any, of CT bronchography for the detection and characterization of benign abnormalities and typical carcinoid tumors of the central airways. MATERIALS AND METHODS: We used bronchoscopy and helical CT to examine 238 bronchial sections in 28 patients with 32 bronchial abnormalities and in five patients with normal bronchoscopy results. Postprocessing consisted of CT bronchography based on surface rendering. Images were interpreted independently by two observers (a radiologist and a pneumonologist) who were not informed of the bronchoscopy results. After initial interpretation of axial CT scans, the observers analyzed the axial CT scans with CT bronchograms. Results were evaluated for gain in diagnostic accuracy and in confidence. RESULTS: Mean sensitivity for detection of abnormal bronchial sections was 89% (range, 87-90%) for axial CT and 92% (range, 90-94%) for axial CT with CT bronchography (not significant). Mean specificity of both approaches exceeded 99%. A correct diagnosis of the nature of the bronchial abnormalities was proposed for 68% of the cases in which axial CT was used alone and in 76% in which both axial CT and CT bronchography were used (not significant). The addition of CT bronchography significantly increased the confidence of the pneumonologist in the diagnoses. CONCLUSION: Axial CT remains the technique of choice to detect and characterize benign abnormalities of the airways. CT bronchography provides little diagnostic gain but increases the confidence of chest physicians in the interpretation of CT scans for the assessment of benign abnormalities and typical carcinoids of the central airways.
The different three dimensional reconstructions of the upper airways that can be obtained with spiral computed tomograpy (CT) are presented here. The parameters indispensable to achieve as real as possible spiral CT images are recalled together with the advantages and disadvantages of the different techniues. Multislice reconstruction (MSR) produces slices in different planes of space with the high contrast of CT slices. They provide information similar to that obtained for the rare indications for thoracic MRI. Thick slice reconstructions with maximum intensity projection (MIP) or minimum intensity projection (minIP) give projection views where the contrast can be modified by selecting the more dense (MIP) or less dense (minIP) voxels. They find their application in the exploration of the upper airways. Surface and volume external 3D reconstructions can be obtained. They give an overall view of the upper airways, similar to a bronchogram. Virtual endoscopy reproduces real endoscopic images but cannot provide information on the aspect of the mucosa or biopsy specimens. It offers possible applications for preparing, guiding and controlling interventional fibroscopy procedures.